This method will check if your app has been installed from the Play Store

 boolean verifyInstallerId(Context context) {

    // A list with valid installers package name

    List<String> validInstallers = new ArrayList<>(Arrays.asList("com.android.vending", "com.google.android.feedback"));

    // The package name of the app that has installed your app

    final String installer = context.getPackageManager().getInstallerPackageName(context.getPackageName());

    // true if your app has been downloaded from Play Store 

    return installer != null && validInstallers.contains(installer);

}